High performance gas turbine engines require cooling passages and cooling flows to ensure reliability and cycle life of individual components within the engine. For example, to improve fuel economy characteristics engines are being operated at higher temperatures than the material physical property limits of which the engine components are constructed. These higher temperatures, if not compensated for, oxidize engine components and decrease component life. Cooling passages are used to direct a flow of air to such engine components to reduce the high temperature of the components and prolong component life by limiting the temperature to a level which is consistent with material properties of such components.
Conventionally, a portion of the compressed air is bled from the engine compressor section to cool these components. Thus, the amount of air bled from the compressor section is usually limited to insure that the main portion of the air remains for engine combustion to perform useful work.
As the operating temperatures of engines are increased, to increase efficiency and power, either more cooling of critical components or better utilization of the cooling air is required.
The present invention is directed to overcome one or more of the problems as set forth above.